What is muzzle energy?
 

I have always used muzzle energy on Midway's site to compare or measure the "worth" of one load to another or one caliber to another. I thought this was pretty accurate until I started researching the .460 Rowland. Several claim it has the power of the 44 mag, but when I research the 44 mag I come up with velocities in the 1500's and energy in the 1200's. When I research the 460, the velocities are similar, but the energy levels at the highest are in the 800's.

Now either my method of comparison is not accurate or the 460 Rowland is being misrepresented.

So can someone explain or point me in the right direction so I understand on what the data actually means for ammo?

Thanks
Darin

Muzzle Energy is an estimate of the kinetic energy of a projectile given its Mass (m) and Velocity (v). In rough terms the Energy is a function of mass and velocity, simple physics...E=1/2mv^2. Differences in expression, i.e. foot-pounds, etc require some additional math for comparing one cartridge to another.

Try this site for example and more reading

Muzzle Energy Calculator

The bullet weight in grains is a intricate part of the formula.

So given that data it is possible for a (now this is a extreme comparison) .22 projectile and a .50 projectile both to have 2000 ft/lbs of energy, but just based on mass alone they would not have the same impact on a soft target. Kind of like a freight train versus a Toyota Camry hitting the same object. Their force is per square foot not total energy exchanged.

Thanks

Possible...maybe, likely...no. .22 and .50 are calibers which have no direct bearing on energy as measured in foot-pounds. In theory a 230 gr .22 and .50 caliber bullet leaving a muzzle at 890 fps would have the same energy. Of course the .22 would need to be much longer or denser to achieve 230 grains of mass in .22 caliber. The damage caused from tissue displacement, trauma, etc is, of course, different for each caliber but the initial energy transfer would be the same. Just as an example, a grain of sand traveling through the vacuum of space at 22,000 MPH can take out a satellite. In this case the energy is skewed towards velocity, not mass but the effect is the same. Another example would be the 30mm cannon on the A-10. A depleted Uranium round is used for tank-busting because of the difference in energy over the standard 30mm round. This time its the mass of the Uranium that ups the energy.

I think I wrote that wrong. My comparison would be better worded as a 250 grain .50 cal traveling at 2500 fps would have the energy of about 2200 lbs and a 50 grain .223 traveling at 4500 fps would have roughly that same 2200 lbs.

If I understand you correctly, even though those two rounds have the same energy they will not have the same impact due to their difference in mass. The smaller bullet would simply pass through the target because it cannot transfer their energy as quickly as the larger object.

Not trying to be a pain, I just want to make sure I understand the basic premise before I go out and research.

That's mostly correct. The mass and velocity differences of the 2 rounds results in the same energy...the caliber determines the surface area over which that energy is transferred. In your example you are correct in assuming that the smaller caliber, faster moving projectile will pass through more readily that the bigger, slower moving round (assuming neither are hollow points or bullet types designed to deliver maximum energy transfer when any hydrostatic pressure, i.e. flesh and blood, is encountered). Think of a baseball and a knife, can't stab anyone with a baseball because the force is distributed over the contact point which is obviously smaller in a knife. Kevlar works in a similar manner by distributing the energy over a large surface area thereby preventing penetration, but leaving one hell of a bruise due to the energy release which cannot be abated or reduced, thank you Mr. Einstein. :)

.223s don't pass through a soft target, they tumble and frag. Ugly wound channel!

Yes but kick that baseball up from 87 mph to 3,200 fps. I think penetration will occur thank you Mr. Einstein. :)

Absolutely...anything moving fast enough will penetrate. The baseball analogy was meant to distinguish the relative ease with which a needle or knife can be made to penetrate flesh with little force because all the force is focused to a small area compared to that of a baseball.